Paper-making screen having at least its warp threads composed of phosphorusbronze alloys



United States Patent PAPER-MAKING SCREEN HAVING AT LEAST ITS WARP THREADS COMPOSED OF PHOSPHORUS- BRONZE ALLOYS Lothar Bangert, Oswaldshalde, Nagold, Wurttemberg, Germany, assignor to Dr. Bangert & Theurer K.G., Hermann Finckh and Hermann Wangner, Nagold and Reutlingen, Germany, all corporations of Germany N0 Drawing. Filed Nov. 22, 1963, Ser. No. 325,774

7 Claims. (Cl. 29-183) This invention relates to improvements in wire and metallic screens, belts, gauzes, fabrics or cloth composed thereof, for use particularly in paper-making machines such as Fourdrinier or cylindrical paper-making machines.

The screens used in paper-making machines are usually composed of phosphor-bronze alloys consisting essentially of copper with 6% to 8% by weight of tin and a small amount, such as 0.1% to 0.4% by weight of phosphorus. The life of such screens in their use in the manufacture of paper, cardboard, etc., is however limited to a few days because the alloy of which the wires are composed has but a limited resistance to wear. The screens, etc., have therefore to be constantly repaired or replaced which requires the machinery to be shut down, and this increases the costs of production.

The inclusion in the phosphor-bronze alloys above referred to of about 1% to by weight of manganese, improves the wearing properties of paper-making screens made therefrom, but only to a limited degree and accordingly phosphor-bronze alloys modified in this manner have not been put to any extended practical use.

These difficulties are overcome in accordance with the present invention by the provision of new wear-resistant screens, etc, formed of the phosphor-bronze alloys above indicated which include iron as well as manganese. The object of the present invention, therefore, is to provide wire, filaments, threads or yarns composed of said improved phosphor-bronze alloys. A further object is to provide wire screens, belts or the like for use particularly in paper-making machinery, in which at least the warp threads are composed of wire formed from the improved phosphor-bronze alloys in question.

The inclusion of iron in the alloy increases the life of the paper-making screens formed at least 30% as compared with screens made of alloys which are free from iron, while the corrosion-resistant qualities of the new screens of this invention are fully equal and to some extent superior to those of the iron-free phosphor-bronze alloys.

The improved screens in accordance with this invention are made of alloys which have the following general composition in parts by weight:

Percent Tin 6 to 14 Phosphorus 0.1 to 0.8 Manganese 0.1 to 3 Iron 0.1 to 1.5 Copper The remainder 3,279,899 Patented Oct. 18, 1966 As indicated earlier, it is desirable that at least the warp threads in a metallic screen or cloth be composed of the new improved alloys of this invention. The filler, woof or weft wire can, if desired, be formed of other materials.

Example (in parts by weight) are hot rolled into rods of about 10 to 13 mm. diameter. Castings of 12 to 13 mm. diameter can also be done directly in the continuous casting process. The rods are then drawn over several stages in the usual manner into wire 0.8 mm. diameter. Wire coils formed from such wire .are then annealed at a temperature of 700 C. Then from this Wire a fabric is produced on a wire loom, for example a wire cloth for removing the water from paper pulp in the wet part of a paper-making or Fourdrinier machine.

This wire fabric has an excellent wear-resistance which is far above that of the usual phosphor-bronze, as well as above that of manganese-containing phosphor-bronzes. It is not known with certainty why this very large increase in wear-resistance and resistance to abrasion occurs. The value selected for the iron content represents a compromise since the resistance to abrasion and hence, the life of the wire fabric increases with increased iron content, while inversely the breaking tension, i.e., the toughness, decreases with increased iron content. Thus by appropriate control of the iron and tin content, the life of the wire fabric can be correspondingly controlled.

Prior art phosphor-bronze results in wire fabrics, the life of which varies greatly from shipment to shipment so that it was heretofore difiicult to pre-determine with certainty when a Wire screen should be renewed. In contrast the alloys according to the present invention are characterized by a small variation in their resistance to abrasion and thus in the life of the fabric.

Although within the above-mentioned limits for the components of the alloy, alloys of excellent suitability for the present use are usually obtained the following specific examples are given:

Percent Percent Percent Percent Remainder tin manganese iron phosphorus 8.5 1. 3 0.2 0. 4 Copper 9. 5 1. 3 0. 2 0. 4 Do. 10.5 1.3 0.2 0.4 Do. 12 1. 3 0. 2 0. 4 Do. 14 1. 3 0. 2 0. 4 Do. 8. 5 1. 5 0. 4 0. 4 Do. 9. 5 1. 5 0. 4 0. 4 Do. 10.5 1.5 0.4 0.4 Do. 12 1. 5 0. 4 0. 4 Do. 14 1. 5 0. 4 0. 4 Do.

I claim:

1. Paper-making screen having at least its warp threads formed of an alloy consisting of 6% to 14% by weight tin, 0.1% to 0.8% by weight phosphorus, 0.1% to 3.0% by Weight manganese, 0.1% to 1.5% by weight iron, and the balance of copper.

2. Paper-making screen .as in claim 1; wherein the amount of said tin in said alloy is at least 7.5% by weight.

3. Paper-making screen as in claim 1; wherein the amount of said iron in said alloy is in the range beamount of said tin in said alloy is at least 8.5% by tween 0.3% and 0.5% by weight. weight.

4. Paper making screen as in claim 1; Where-in the References Cited by th Examiner amount of said manganese in said alloy i in the range 5 UNITED STATES PATENTS between 0.7% and 2.0% by weight.

15. Paper-making screen as in claim 1; wherein the 2128954 1 3 Montgomery amount of said manganese in said alloy is in the range 2128955 9/ 9 8 Montgomery between 1.0% and 1.5% by weight. 2829968 4/1958 75 154 2,918,094 12/1959 Preynik 75--154 6. Paper-making screen as in claim 1; wherein the 10 amount of said iron in said alloy is in the range between x 0.2% and 0.6% by Weight. DAVID L. RECK, P1 zmaly Examiner.

7. Paper-making screen as in claim 1; wherein the DEAN, Assistant Examiner- 

1. PAPER-MAKING SCREEN HAVING AT LEAST ITS WRAP THREADS FORMED OF AN ALLOY CONSISTING OF 6% TO 14% BY WEIGHT TIN, 0.1% TO 0.8% BY WEIGHT PHOSPHORUS, 0.1% TO 3.0% BY WEIGHT MANGANESE, 0.1% TO 1.5% BY WEIGHT IRON. AND THE BALANCE OF COPPER. 